Unlocked fps range in game: 35-114, why is it dipping to 28 when I lock it to 30?

[astheoceansblue]

I'm currently paying Batman Arkham Knight on PC. The game has its share of issues, so I'm sure this is related, but it's something I haven't seen before.

If I unlock my frame rate, the game ranges between 35-114.
If I lock the frame rate with Rivatuner to 30, the game dips every few second to 28-29, with occasional drops into the low 20s.

Why is it dipping under my unlocked range? I was under the impression that locking underneath your minimum fps would mean it would remain absolutely stable.

Current system:
i52500k@4.2ghz
MSI 970 +200/500
8gb ram
SSD

Thanks in advance.

 

[toot12311]

Its just how shitty the port is thats the only answer you are going to get.
I doubt its a hardware problem

 

[astheoceansblue]

But why would locking with rivatuner allow it to dip below the unlocked range?

 

[guanyu210379]

That is why WB pulled the game from Steam.
I tried removing the fps cap but the game falls down to one digit fps every several seconds, hence heavy stutters.
After some a driver updates, it dropped down sometimes to slightly below 20 fps but ...that still sucks.
I went for refund and everything is ok now...hehehehehe

I am still busy with Witcher 3 anyhow. Witcher 3 is the game of all games so far in 2015. It is the complete opposite of Arkham Knight. Excellent optimization, relative bug free, tons of free DLCs, etc.

 

[astheoceansblue]

I'm asking about this specific situation.

Forget for a moment that this is ArKham Knight, I'm curious about the technical reason, how it's possible for something to dip when you're locked underneath your lowest fps?

If my machine never dips below 35 when it's unlocked, how is it even possible to drop below 30 when I lock it with an external tool?

 

[astheoceansblue]

I've noticed something:

Whatever I lock the fps to, the frames will drop by 1-2 constantly.

If I lock to 30, it flits between 28-30. If I lock to 32 it flits between 30-32, and so on.

Any idea what could be causing this?

 

[MarkW]

Think about your video card as if it was a car. Now this car has to get you from point A to point B. But you decide to get off of the highway, and instead take a route across the back country. There is no road here. You are out in the wilds. And you decide to set the cruise control to 60.

Do you think that your car can drive through the wilds at a absolute 60 MPH/KPH despite the fact that you are encountering boulders, creeks and rivers, river banks, and mountains on this trip?

Of course not. And when you play a game, your video card is experiencing the same problems. Some scenes are easy to draw, so they are drawn quickly, and then the scene changes, and things are a lot more complex, and it takes the video card longer to draw that scene. Sometimes it takes 10 times longer than the scene it was showing just a half second earlier. And so things slow down.

You cannot force a video card to have an absolute minimum number of frames. It will take the time it needs to complete each and every frame, and just because you told it to do a minimum of 30 frames means nothing to the video card. What is it supposed to do? Only draw out part of the frame to keep the frame rate where you want it? No. That will not happen. Even a Titan X will slow down on certain scenes. Every video card does, and always has. And at least for the next 15 years, probably will continue to do so.

Maybe someday, in the far distant future, video cards will be able to produce scenes that appear to be real life movies without ever slowing down below some preset number of frames per second. But that does not happen today even on the most expensive video cards available, even when you run 4 of those expensive cards in SLI or Crossfire. That kind of setup will reduce the slowdowns by a lot, but they will still happen in some games. Accept it. That is how things work today. And how things will continue to work for a very long time.

 

[astheoceansblue]

Think about your video card as if it was a car. Now this car has to get you from point A to point B. But you decide to get off of the highway, and instead take a route across the back country. There is no road here. You are out in the wilds. And you decide to set the cruise control to 60.

Do you think that your car can drive through the wilds at a absolute 60 MPH/KPH despite the fact that you are encountering boulders, creeks and rivers, river banks, and mountains on this trip?

Of course not. And when you play a game, your video card is experiencing the same problems. Some scenes are easy to draw, so they are drawn quickly, and then the scene changes, and things are a lot more complex, and it takes the video card longer to draw that scene. Sometimes it takes 10 times longer than the scene it was showing just a half second earlier. And so things slow down.

You cannot force a video card to have an absolute minimum number of frames. It will take the time it needs to complete each and every frame, and just because you told it to do a minimum of 30 frames means nothing to the video card. What is it supposed to do? Only draw out part of the frame to keep the frame rate where you want it? No. That will not happen. Even a Titan X will slow down on certain scenes. Every video card does, and always has. And at least for the next 15 years, probably will continue to do so.

Maybe someday, in the far distant future, video cards will be able to produce scenes that appear to be real life movies without ever slowing down below some preset number of frames per second. But that does not happen today even on the most expensive video cards available, even when you run 4 of those expensive cards in SLI or Crossfire. That kind of setup will reduce the slowdowns by a lot, but they will still happen in some games. Accept it. That is how things work today. And how things will continue to work for a very long time.

Thanks for your long winded analogy, but it missed the point entirely.

When I unlock the framerate, it never ever falls below 35. That's the bare minimum it hits.

So why when I lock it //below// the bare minimum does it choose a new bare minimum?

It never went below 35 before, so why is it now?

 

[bystander]

This is why you are dipping below 30 FPS when you lock it at 30. When you lock the FPS to 30, what limiter is really doing is locking to the frame time that 30 FPS has, which is 33.3ms per frame. If every frame can be made within 33.3ms, you'd have 30 FPS, but occasionally, you get a frame that takes longer than 33.3ms to render. This will cause the FPS to drop below 30 due to a few frames which take longer to render.

Without the FPS limiter, you may also have frames which render faster than 33.3ms which help boost the FPS past 30, but because the limiter prevents that, you won't get those boosts, only the drops.